WASHINGTON — President Donald Trump stepped up his attack on federal environmental protections Tuesday, issuing an order directing his administration to begin the long process of rolling back sweeping clean water rules that were enacted by his predecessor.

The order directing the Environmental Protection Agency to set about dismantling the Waters of the United States rule takes aim at one of President Barack Obama's signature environmental legacies, a far-reaching anti-pollution effort that expanded the authority of regulators over the nation's waterways.

The contentious rule had been fought for years by farmers, ranchers, real estate developers and other industries, which complained it invited heavy-handed bureaucrats to burden their businesses with onerous restrictions and fines for minor violations.

Obama's EPA argued that such claims were exaggerated and misrepresented the realities of the enforcement process of a rule that promised to create substantially cleaner waterways and with them, healthier habitats for threatened species of wildlife.

The directive to undo the clean water initiative is expected to be closely followed by another aimed at unraveling the Obama administration's ambitious plan to fight climate change by curbing power plant emissions.

"It is such a horrible, horrible rule," Trump said as he signed the directive Tuesday aimed at the water rules. "It has such a nice name, but everything about it is bad." He declared the rule, championed by environmental groups to give the EPA broad authority over nearly two-thirds of the water bodies in the nation, "one of the worst examples of federal regulation" and "a massive power grab."

While the executive orders are a clear sign of the new administration's distaste for some of the highest profile federal environmental rules, they also reflect the challenge it faces in erasing them. Both the climate and the clean water rules were enacted only after a long and tedious process of public hearings, scientific analysis and bureaucratic review. That entire process must be revisited before they can be weakened. It could take years.

And environmental groups will be mobilized to fight every step of the way. "These wetland protections help ensure that over 100 million Americans have access to clean and safe drinking water," California billionaire climate activist Tom Steyer said in a statement. "Access to safe drinking water is a human right, and Trump's order is a direct violation of this right."

The executive orders are compounded by the administration's release of a budget blueprint that includes deep cuts at the EPA. Even if the process of changing the environmental rules is slow, the Trump administration will aim to hasten their demise by hollowing out the agencies charged with enforcing them.

At the same time, it is working with Congress to immediately kill some environmental protections under an obscure authority that applies to regulations enacted within the final months of the previous administration. A rule intended to limit water pollution from coal mining has already been killed by Congress, which is now weighing whether to jettison rules that force gas drilling operations on federal land to capture more of the toxic methane they emit.

Trump vowed Tuesday that he would continue to undermine Obama-era environmental protections wherever he sees the opportunity, arguing they have cost jobs. "So many jobs we have delayed for so many years," Trump said. "It is unfair to everybody."

Many industries take issue with that interpretation. Tuesday's order, for example, was met with a swift rebuke from sport fishing and hunting groups. They said the clean water rule has been a boon to the economy, sustaining hundreds of thousands of jobs in their industry.

"Sportsmen and women will do everything within their power to compel the administration to change course and to use the Clean Water Act to improve, not worsen, the nation's waterways," a statement from a half-dozen of the organizations said.